Location: Application Technology ResearchTitle: CO2 and N2O emissions and microbial community structure from fields that include salt-affected soils
|FIELDER, DOUGLAS - South Dakota State University|
|CLAY, DAVID - South Dakota State University|
|JOSHI, DEEPAK - South Dakota State University|
|BHATTARAI, DWARIKA - South Dakota State University|
|REESE, CHERYL - South Dakota State University|
|BRUGGEMAN, STEPHANIE - South Dakota State University|
|JAKUBOWSHI, DUNCAN - South Dakota State University|
|CLAY, SHARON - South Dakota State University|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2021
Publication Date: N/A
Interpretive Summary: Saline/sodic soil problems are increasing and will decrease long-term food security. More N2O-N and less CO2-C were emitted from saline/sodic soil than productive soils. Five times more fertilizer-derived N was lost from the saline/sodic than the productive zone, explained by a significant increase in denitrification gene copy numbers detected in the saline/sodic soil.
Technical Abstract: Although salinity and sodicity are world-wide problems, information on greenhouse gas emissions from agricultural salt-affected soils is scarce. The CO2-C and N2O-N emissions were quantified from three zones (treatments) dispersed within a single Northern Great Plains USA field:, a highly productive zone (EC 1:1 = 0.4 dS m-1; SAR= 1.8), a transition zone (moderately salt-affected) (EC1:1=1.6 dS m-1; SAR = 4.99), and a saline/sodic zone (EC1:1 = 3.9 dS m-1; SAR = 22). In each zone, emissions were measured every 4 hours for 7 days in 4 randomly placed chambers that were treated with 2 N rates (0 and 224 kg N ha-1). The experiment was conducted in 2018 and 2019 during similar seasonal periods. Soil samples taken from treatment zoness after greenhouse gas measurement were analyzed for soil inorganic N, microbial biomass using phospholipid fatty acid analysis (PFLA), and copy numbers of specific microbial denitrification functional genes via real-time PCR. The productive zone had the greatest microbial biomass with the highest CO2-C and lowest N2O-N emissions, whereas the saline/sodic zone had the lowest microbial biomass and the lowest CO2-C and highest N2O-N emissions. Within a zone, urea application did not influence CO2-C emissions, however, N2O-N emissions from the urea-treated saline/sodic zone were 84 and 57% higher than the urea-treated productive zone in 2018 and 2019, respectively. The nitrite reductase gene copy number, nirS, was 64-fold higher in saline/sodic soil compared with productive soil. These findings suggest N2O-N emissions could be reduced by not applying N to saline/sodic zones.